Recently, in order to enable an analysis by using a small amount of a sample, an analyzing tool called a microdevice has been developed keenly. The microdevice is manufactured by, for example, forming a fine channel (a width thereof ranges from several μm to several hundreds μm) and a concave part on one surface of a glass substrate or a resin substrate by utilizing a micromachining technique applied to an integrated circuit (for example, see Patent Document 1).
FIG. 7 is an exploded perspective view showing an example of a conventional microdevice. As shown in FIG. 7, the microdevice is formed by connecting a substrate 51 and a cover 52. The substrate 51 and the cover 52 are formed of an optically transparent material such as a transparent resin and a glass.
Moreover, as shown in FIG. 7, in the cover 52, an inlet 53 that pierces the cover 52 in its thickness direction is formed. The inlet 53 is used for introducing a sample such as blood into an inside of the microdevice. On one surface of the substrate 51, a concave part 54 that has a circular-shaped cross section, a concave part 56 that has a larger cross section than that of the concave part 54, and a channel 55 that connects the concave part 54 and the concave part 56 are provided.
The concave part 54 is formed so as to conform to the inlet 53 of the substrate 51. The concave part 54 functions as a storage part for storing the introduced sample temporarily. In the concave part 56, a solid reagent 57 is disposed. The concave part 56 functions as a reaction cell. The channel 55 functions as a flow path for transferring the sample that is stored in the concave part 54 to the concave part 56.
Moreover, in order to secure ventilation between the concave part 56 and an outside when connecting the substrate 51 and the cover 52, a channel 58 serving as a vent path also is formed on the substrate 51. According to such a structure, in the microdevice shown in FIG. 7, the sample transfers from the concave part 54 to the concave part 56 by utilizing capillary action. Further, the reagent 57 is colored by reacting with a certain component in the sample. Accordingly, if measuring absorbance by irradiating the concave part 56 that serves as the reaction cell with light from the cover 52 side and photoreceiving transmitted light, the density of the certain component in the sample can be determined.
Moreover, in the chemical analysis using the microdevice, which is represented by the example of FIG. 7, temperature control of the reaction cell of the microdevice is important for maintaining a condition of the reaction to be constant. As one method for controlling the temperature of the reaction cell of the microdevice, a method using a heater block is known. According to this method, a whole of the microdevice can be heated uniformly.
However, in the case of using the heater block, the heater block is required to have a sufficiently large heat capacity with respect to a heat capacity of the microdevice. Further, the size of the heater block is in proportion to the heat capacity thereof. Thus, the temperature control using the heater block has problems in that an increase of a size of a measurement apparatus cannot be avoided, and the consumption of an electric power cannot be reduced. Moreover, because of heating from an outside of the microdevice, a temperature of the reaction cell inside the microdevice is expected only from a time of increasing a temperature and a temperature controlling precision of the heater block, and thus it is difficult to control the temperature of the reaction cell strictly.
Whereas, a method in which a metal thin film serving as a heating element and a temperature sensor (a temperature measurement device) such as a thermocouple and a thermistor element are provided inside the microdevice, which are used for heating and measuring the temperature inside the microdevice so as to achieve the temperature control also is known (for example, see Patent Document 2). According to this temperature controlling method, the size of the measurement apparatus can be decreased, and the consumption of electric power can be reduced. Further, since the microdevice can be heated from its inside, and the temperature thereof can be measured inside the microdevice, the temperature control of the reaction cell can be achieved more strictly, compared with the case of using the heater block.
Patent Document 1: WO 03/093836 brochure (FIGS. 1 to 40 and 45 to 48)
Patent Document 2: JP 2002-90357 A (FIG. 1)